The present invention relates to adjustable chair parts and more particularly to a mechanism to allow a chair part to be adjusted and the adjustment to be maintained.
Chairs are known to have parts that are adjustable such as the arm rests, the seat and the backrest. The height of a backrest, for instance, may be adjusted up or down and, additionally, an angle a backrest makes with reference to the seat may be altered. In many chairs, a person seated in a chair who wishes to change the angle of a backrest moves a handle from a locked position to an unlocked position, releasing a mechanism that maintains the support bar for the backrest at a particular angle. The person may then find a new angle for the backrest support bar and, by returning the handle to a locked position, set the mechanism to maintain the new angle.
Typically, springs bias various adjustable parts to a default position. Unfortunately, when a part of an unoccupied chair is unlocked while significantly offset from its default position, a violent action may ensue as the part returns to its default position. This violent action could cause injury. It is desirable, then, to design a mechanism that avoids this problem.
In accordance with an aspect of the present invention there is provided locking apparatus including a clutch plate and a locking bracket, the locking bracket having a passageway adapted to accept the clutch plate, the passageway including a first channel and a second channel, the first channel allowing movement of the clutch plate along the passageway, the second channel preventing movement of the clutch plate along the passageway.
In accordance with a further aspect of the present invention there is provided a chair including: a chair base; a chair adjustment mechanism, mounted to the chair base, including a locking apparatus comprising a clutch plate and a locking bracket forming a passageway receiving the clutch plate, the passageway including a first channel and a second channel, the first channel allowing movement of the clutch plate along the passageway, the second channel preventing movement of the clutch plate along the passageway; a seat mounted to one of the locking bracket and the clutch plate of the chair adjustment mechanism; a backrest; and a backrest support bar supporting the backrest, mounted to another one of the locking bracket and the clutch plate of the chair adjustment mechanism.